Swamp cooler, internal fermenter temp question

Ok, I brewed pale ale Saturday night. It has been fermenting fine since. Lots of airlock bubbling the first few days, now has slowed down to almost nothing. Seems normal so far.

Since I pitched the yeast, I put the fermenter in the swamp cooler and have maintained the temp of the swamp water to be in the mid 60's. I have a towel wrapped around it that is dipped in the water.

My question is, can anyone guesstimate the internal temp? I don't have a thermometer in the fermenter. Will it be in the mid 60's? Will it be cooler? Should I worry or remove the towel?

I have just been reading that this technique will make it cooler inside then the swamp water temp.

Once active fermentation is over, it should level out to that of ambient temperature around it, which in this case is your swamp cooler. So dont go dumping tons of ice in it trying to pull it down to 60 if theres no fermentation happening anymore, you may overshoot and put the yeast to sleep.

So the beer wont get cooler then the swamp water? Cause I have my swamp water to what I want it ~65*. I'm fine with that, as long as my beer doesn't get cooler then the swamp water...

During fermentation the beer is exothermic (gives off heat), so the beer is warmer than the swamp water. Once fermentation is 100% done, it should be the same temp.

Fyi: I have a infrared thermometer. I used a swamp cooler for th first time a few weeks ago. In my swamp cooler my water level was below the top of the beer by couple inches.. Using the IR thermometer I can easily compare the beer temp to the swamp water temp by aiming at the side of the bucket just above the water level. The first few days after the yeast pitch the beer was a couple degrees warmer.

Greg

chungking said:

So the beer wont get cooler then the swamp water? Cause I have my swamp water to what I want it ~65*. I'm fine with that, as long as my beer doesn't get cooler then the swamp water...

Click to expand...

Probably not, but theoretically, it could, if the towel is draped over the fermenter is just touching the water enough to keep it wet, the process of evaporation could actually pull heat from the beer. Evaporation will cause cooling on the towel. Depending on how deep the beer is in the swamp cooler though, the volume of water will likely keep a constant temp of the water. If you just had a little water in the swamp cooler, just enough to keep the towel wet, you could see actual cooling. Not much though, the volume of beer is going to be hard to drop temperature with a passive cooling system like evaporation, without actually cooling the water itself.

Ok thanks for the responses. I have the swamp water filled a little above half way, with the towel ends in the swamp water. The swamp water has been super consistent. Just was wondering if the evaporation process was cooling my beer below the 59*f lower yeast limit or not...

The evaporation doesn't contribute a whole lot to the cooling, but what it does contribute is observable. The temperature of the towel is not going to be any lower than the temperature of the beer.

Also because water conducts heat much better than air, the temperature of the water will be very close to that of the beer.

Here's some analysis of my swamp cooler setup:
http://woodlandbrew.blogspot.com/2012/09/swamp-cooler.html

WoodlandBrew said:

The evaporation doesn't contribute a whole lot to the cooling, but what it does contribute is observable.
http://woodlandbrew.blogspot.com/2012/09/swamp-cooler.html

Click to expand...

What cooling effect do you think a swamp cooler has other than evaporation?

Other than that, all I can think that it would do is act a buffer between the ambient air and the beer. (ie. If you have a room that warms up too much, then too cool, using a outer bucket full of water would act to slow down the heat transfer to/from the beer and therefore keep it more stable.)

Greg

That's it Greg. It hold temperature well because it is a larger thermal mass. Many people add ice to drop the temperature further.